ci: restructure Enhanced Vision tests into 6 functional CI groups #178

Job	Run time
Build Khronos OpenVX sample	52s
Build rustVX (main)	1m 40s
build	1m 49s
vision-statistics	10s
graph	10s
vision-filters	58s
vision-color	12s
vision-arithmetic	25s
image-ops	11s
data-objects	14s
KHR extension: user-data-object	22s
baseline	13s
Enhanced-Vision: Control Flow	11s
vision-features	18s
Enhanced-Vision: Tensor Arithmetic	9s
vision-geometric	34s
Enhanced-Vision: Tensor Transforms	8s
Enhanced-Vision: Feature Extraction	12s
Enhanced-Vision: Post-Processing	11s
Enhanced-Vision: Advanced Filtering	59s
Perf gate (PR vs main)	2m 34s
vision-pyramid	16s
Benchmark & compare (rustVX vs Khronos sample)	4m 33s
	17m 21s

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